In industrial settings, control systems are used to monitor and control inventories of industrial and chemical processes and the like. Typically, the control system performs these functions using field devices distributed at key locations in the industrial process and coupled to control circuitry in the control room by a process control loop. The term “field device” refers to any device that performs a function in a distributed control or process monitoring system, including all the devices used measurement, control and monitoring of industrial processes. In such industrial processes, substances such as liquids, slurries, or solids are often stored in large holding or processing tanks. One exemplary type of field device is able to measure the height of a material in a tank and provide an indication of such tank level over a process control loop. Another exemplary type of field device may measure a pressure or flow of liquid flowing through a conduit such as a pipe, and provide such indication over a process control loop. Often, however, it is also useful to provide a local indication of the process variable such that a technician or operator walking near the tank or field device can quickly obtain a visual indication relative to the process variable without needing to interrogate the field device through process communications. One way in which this visual indication has been provided, with respect to tank level indication, is by using a magnetically operated indicator.